/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package async;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicInteger;

import javax.servlet.AsyncContext;
import javax.servlet.AsyncEvent;
import javax.servlet.AsyncListener;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import async.Stockticker.Stock;
import async.Stockticker.TickListener;

@douyu.mvc.Controller
public class AsyncStock implements TickListener, AsyncListener {

	public static final String POLL = "POLL";
	public static final String LONG_POLL = "LONG-POLL";
	public static final String STREAM = "STREAM";

	static ArrayList<Stock> ticks = new ArrayList<Stock>();
	static ConcurrentLinkedQueue<AsyncContext> clients = new ConcurrentLinkedQueue<AsyncContext>();
	static AtomicInteger clientcount = new AtomicInteger(0);
	static Stockticker ticker = new Stockticker();

	public AsyncStock() {
		System.out.println("AsyncStockServlet created");
	}

	public void index(final HttpServletRequest req, final HttpServletResponse resp) throws IOException {
		if (req.isAsyncStarted()) {
			req.getAsyncContext().complete();
		} else if (req.isAsyncSupported()) {
			AsyncContext actx = req.startAsync();
			actx.addListener(this);
			resp.setContentType("text/plain");
			actx.setTimeout(3000);
			clients.add(actx);
			if (clientcount.incrementAndGet() == 1) {
				ticker.addTickListener(this);
			}
		} else {
			new Exception("Async Not Supported").printStackTrace();
			resp.sendError(400, "Async is not supported.");
		}
	}

	@Override
	public void tick(Stock stock) {
		ticks.add((Stock) stock.clone());
		Iterator<AsyncContext> it = clients.iterator();
		while (it.hasNext()) {
			AsyncContext actx = it.next();
			writeStock(actx, stock);
		}
	}

	public void writeStock(AsyncContext actx, Stock stock) {
		HttpServletResponse response = (HttpServletResponse) actx.getResponse();
		try {
			PrintWriter writer = response.getWriter();
			writer.write("STOCK#");//make client parsing easier
			writer.write(stock.getSymbol());
			writer.write("#");
			writer.write(stock.getValueAsString());
			writer.write("#");
			writer.write(stock.getLastChangeAsString());
			writer.write("#");
			writer.write(String.valueOf(stock.getCnt()));
			writer.write("\n");
			writer.flush();
			response.flushBuffer();
		} catch (IOException x) {
			try {
				actx.complete();
			} catch (Exception ignore) {/* Ignore */
			}
		}
	}

	@Override
	public void onComplete(AsyncEvent event) throws IOException {
		if (clients.remove(event.getAsyncContext()) && clientcount.decrementAndGet() == 0) {
			ticker.removeTickListener(this);
		}
	}

	@Override
	public void onError(AsyncEvent event) throws IOException {
		event.getAsyncContext().complete();
	}

	@Override
	public void onTimeout(AsyncEvent event) throws IOException {
		event.getAsyncContext().complete();
	}

	@Override
	public void onStartAsync(AsyncEvent event) throws IOException {
		// NOOP
	}
}
